Influence of real gas effects on shockwaves in shock tube

Supercritical carbon dioxide (SCO₂) is carbon dioxide that is maintained at a pressure and temperature higher than its critical point values, 71.37 bar and 304.25 K respectively. SCO₂ properties are predicted with the real gas model and its applications mostly involve high speed flows. The real gas properties of Supercritical CO₂ and compressible flow increases the complexity of the shockwave problem and study of such problems are called non-ideal compressible fluid dynamics (NICFD). Shock tubes are used to study high speed gas dynamics by generating a shock wave to rapidly heat and compress a test gas. This present work investigates the influence of real gas effects on the run time in a shock tube using computational fluid dynamics simulations. The shock wave dynamics of CO₂ is studied at gaseous state, supercritical state and their combination. Simulations were performed with different pressures for each state in the driver and driven sections at pressure ratio of 3. The run time was determined from x-t diagrams showing the timing of the incident shock reflection at the end wall and the arrival of the expansion wave. This present work demonstrates that manipulating the phase of medium is an effective strategy for increasing run times in shock tubes. Further comparison of shock wave dynamics at different state gives an insight into the non-ideal compressible fluid dynamics.